OPTIMIZATION OF THE INHIBITION EFFICIENCY OF BITTER KOLA LEAF EXTRACT AS CORROSION INHIBITOR OF MILD STEEL IN H2SO4.

Summary

This work is on the optimization of the inhibition efficiency of bitter kola leaf extract as corrosion inhibitor of mild
steel in H2SO4. Gravimetric method was employed in the corrosion inhibition study. It was supplemented by Fourier
transform infrared (FTIR) spectrophotometric and scanning electron microscopic analyses of the plant extract and
mild steel surface respectively. Response surface methodology (RSM) was applied in the optimization process. Central
composite design tool of design expert software 9 was used to evaluate the effects and interactions of four variables of
acid concentration (AC), inhibitor concentration (IC), temperature (T) and time (t) on the inhibition efficiency of the
extract. Analysis of variance (ANOVA) was used to study the data generated. From the analyses of the experimental
results, it was observed that there was a synergy among the functional groups of O-H, C-H, C=C and N-H in the
corrosion inhibition process. Bitter kola leaves extract exhibited optimum inhibition efficiency of 83.56 % obtained at
optima acid concentration of 1.2 M, inhibitor concentration of 0.9 g/l, temperature of 300 K and time of 21 hours. The
extract is highly efficient in surface treatment of the mild steel in H2SO4 medium.

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